clark@randvax.UUCP (John Clark) (07/18/90)
*Twice* in the past couple of weeks, the 1.4 Mb FDHD drive in my Mac IIcx and a *locked* HD floppy have executed a mutual suicide pact. It is not yet clear "who pulled the trigger." This has--among other things--shaken my faith in the integrity of locked diskettes. The first drive was about a year old when it failed; the second one lasted less than two weeks. The symptoms and circumstances of these events are virtually identical. A locked, formatted HD floppy (Sony), with files stored on it, suddenly went bad. The damage was apparently real, as the diskette elicited the same initialization dialog from another Mac on which I tried to mount it. I ran SUM II (Symantec Utilities for the Mac), in an attempt to recover the files on the damaged diskettes. On one diskette, SUM II found some--but not all--of the files, and recovered them successfully; for the other diskette, SUM II cound not recover anything. In both cases, subsequent attempts to recover files using other methods in SUM's bag of tricks resulted in protracted diskette drive activity which I halted via SUM's "Stop" button. For the first diskette, I waited a couple of hours, as the progress thermometer was moving (albeit slowly); for the second diskette, I was impatient to do other things, so I stopped the process after a couple of minutes. In both cases I ejected the floppy. The destruction of the drive and floppy evidently occurred during this period of drive activity. Examination of the just-ejected (and locked, recall) floppy revealed visible physical damage to the media! Magnetic material had apparently been removed from the surface of the rotating flexible substrate, as evidenced in translucent, white-colored, uneven, annular bands. One diskette had a single band about 1/8 inch wide; the other had two widely separated bands, each less than 1/32 inch wide. From this point on, the drive would not recognize *any* floppy; the only response was the initialization dialog. Restarting, shutting down, trying many different floppies, all made no difference. I tried initializing various fresh diskettes (1.4 Mb, 800 Kb, 400 Kb); all such attempts were quickly terminated with "initialization failure." Judging by the destroyed floppies, I could readily visualize clumps of magnetic material glopped on the drive's read and/or write heads... So, it seems that my floppy drive (twice) suffered a catastrophic head crash. Is this a common occurrence? I've never heard mention of it for floppies, and it's certainly never happened to me before in 6+ years of Mac'ing. Is the drive to blame? (*Two* drives!?) Something on the motherboard, perhaps? How about SUM II? A virus? (Disinfectant 2.0 found none of the known viruses.) Airborne crud? (My environment isn't unusually dirty/smoky/dusty, but I do leave my Mac on all the time.) I got a good look inside the second failed drive when it was replaced, and it seemed spotlessly clean to the naked eye--no visible accumulations of anything. The two diskettes are Sony-labeled, from different boxes-of-ten, but with the same batch number. System software is 6.0.5; many INITs/cdevs/etc... Any thoughts, suggestions, experiences, etc., that might shed light on this would be most appreciated. In the meantime, having just had my *third* FDHD installed ( :-( ), I am reminded of the importance of frequent backups. I have acquired new respect for the dictum that commercial distribution disks should be locked, hidden away, and *never* inserted in the floppy drive except to make working copies for everyday use. Locking a floppy will not protect against a head crash! (Of course, copy protection schemes that use a key disk--thankfully rare these days--don't even deserve mention...) John Clark clark@rand.org
vladimir@prosper (Vladimir G. Ivanovic) (07/19/90)
I was under the impression that floppy drives suffered "head crashes" all the
time, literally. The heads touch the recording surface making the floppy
travel a sinous path like:
xxxxx
xxxxxx /-----\ xxxxx
----------------/ xxxxx \-------------
xxxxxxx xxxxxx
where the x's represent the heads and the -'s represent the floppy.
-- Vladimir